A handout photo made available by the London Metropolitan Police on the Water,(MPS) showing MPS specialist firearms officers taking part in the major anti terrorist drill, #999Exercise, on the River Thames in east London, England, 19 March 2017. The MPS report that officers stormed a hijacked cruise boat to rescue hostages from six ‘terrorists’, members of the London Fire Brigade, London Ambulance Service and The Royal National Life Boat Institue were also taking part in the event